Coupling element for differential hybrid coupler

ABSTRACT

A coupling element is disclosed, comprising four coils that are arranged such that each one of the coils extends both in a first layer and a second layer. The first layer and the second layer are stacked with respect to each other and separated by an intermediate dielectric layer. The layout of each layer is configured to provide a transformer coupling between a first one and a third one of the coils, and between a second one and a fourth one of the coils. Further, the first coil and the second coil, and the third coil and the fourth coil, respectively, are routed so as to allow a differential signaling. A semiconductor device and a differential hybrid coupler comprising the coupling element are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a non-provisional patent application claimingpriority to European Patent Application No. EP 15174125.3, filed Jun.26, 2015, the contents of which are hereby incorporated by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to a coupling element for couplers andpower dividers, and in particular to a differential coupling elementarranged in a first layer and a second layer that are separated fromeach other by an intermediate dielectric layer. The present disclosurealso relates to a semiconductor device comprising such coupling element,and to a differential hybrid coupler comprising such coupling elementand a termination resistor.

BACKGROUND

Coupling elements include different types of couplers and power dividersin which input electromagnetic power is split to multiple differentoutput ports. In, e.g., R. C. Frye et al., A 2 GHz Quadrature HybridImplemented in CMOS Technology, IEEE JSSC, vol. 38, no. 3, pp. 550-555,March 2003, the input signal is split into two signals that are 90degrees apart in phase. The frequency at which these and other couplersoperate has allowed them to be miniaturized and integrated on-chip, andthere is a still growing interest in further reducing the size orfootprint of couplers implemented in, e.g., wireless communicationsystems.

There is also a general tendency in chip design to reduce the supplyvoltage. A drawback with lower supply voltages is however that the noiseimmunity of the circuits may be impaired, which may reduce the signalingquality. Q. Shi et. al., A 54-69.3 GHz Dual-Band VCO with DifferentialHybrid Coupler for Quadrature Generation, Solid-State CircuitsConference (A-SSCC), 2013 IEEE Asian, pp. 325,328, 11-13 November 2013,provides differential signaling by connecting two single endedquadrature hybrids. Such a duplicated quadrature hybrid however requiresa relatively large area and may increase the footprint of the circuit.

There is hence a need for a coupler that has a relatively smallfootprint and that is less sensitive to noise, e.g. external noiseand/or noise induced from the power supply and/or neighboring circuits.

SUMMARY

An object of at least some of the embodiments of the present disclosureis to provide a coupling element that is less sensitive to noise and hasa relatively small footprint.

At least one of this and other objects of the present disclosure isachieved by means of a coupling element having the features defined inthe independent claim. Additional embodiments of the disclosure arecharacterized by the dependent claims.

According to a first aspect of the present disclosure, a couplingelement is provided that comprises four coils and is arranged in a firstlayer and a second layer. The first layer and the second layer areseparated from each other by an intermediate dielectric layer. The firstcoil is arranged such that at least one turn extends in the first layerand another turn extends in the second layer. Similarly, the second coilis arranged such that at least one turn extends in the first layer andanother turn extends in the second layer. The at least one turn of thesecond coil arranged in the first layer is further arranged along atleast a portion of the first coil arranged in the first layer, whereinthe another turn of the second coil arranged in the second layer isarranged along at least a portion of the first coil arranged in thesecond layer. The third coil is arranged such that at least one turn ofthe third coil extends in the first layer and superposes at least aportion of the first coil arranged in the second layer, and such thatanother turn of the third coil extends in the second layer and issuperposed by at least a portion of the first coil arranged in the firstlayer. The fourth coil is arranged such that at least one turn of thefourth coil extends in the first layer and superposes at least a portionof the second coil arranged in the second layer, and such that anotherturn of the fourth coil extends in the second layer and is superposed byat least a portion of the second coil arranged in the first layer.

A “turn” should be understood as a portion of a conductive track ortrace forming a part of the coil and extending in a given plane of thecoupling element. The turn may extend along a curve starting and endingon a same side of a plane laterally dividing the coupling element in twohalves. In some embodiments, the turn may extend along a curve making atleast a 180° turn or loop. In other embodiments, the curve may make afull 360° turn. The curve along which the track of the coil extends maybe formed as a spiral starting at a first radial distance from a centerof the coupling element and ending at a second radial distance from thecenter point.

By arranging the coils of the coupling element in two separate layersarranged above each other, the footprint or total area of the couplingelement may be reduced, which hence allows for more compact devices andcircuits to be provided.

Further, by arranging the coils such that the first coil extends atleast partly along the second coil in the same plane, i.e., along,abreast, or parallel with the second coil in the first layer and thesecond layer, respectively, a parasitic capacitance, or shuntcapacitance, may be provided between the conductors or traces of thefirst coil and the second coil. The first coil and the second coil maybe provided with a differential signal, wherein two complementarysignals are transmitted through the first and second coils,respectively.

The first coil and the second coil may be routed in opposite directionsin relation to each other, i.e., such that a signal in the first coiland a signal in the second coil during operation are transferred inopposite directions relative to each other. A magnetic field generatedby the first coil may thereby be prevented from counteracting a magneticfield generated by the second coil, and vice versa, during differentialoperation of the coupling element.

Similarly, arranging the third coil such that it in a given planeextends at least partly along or abreast the fourth coil in the sameplane, respectively, a parasitic capacitance may be provided between theconductors or traces of the first coil and the second coil. The thirdcoil and the fourth coil may, just as the first and second coils, berouted in opposite directions to each other so as to not counteract amagnetic field generated by the third coil and the fourth coil,respectively, during differential operation.

In an example embodiment, an electromagnetic interaction may also beachieved between the first coil and the third coil extending above oralong each other in separate planes, i.e., between the first coil in thefirst layer and the third coil in the second layer, and vice versa.

The electromagnetic interaction between two coils that are separatedfrom each other by the intermediate dielectric layer may hence provide atransformer coupling between said coils. Thus, a transformer couplingmay be provided between the first coil and the third coil. Similarly, atransformer coupling may be provided between the second coil and thefourth coil.

It will be appreciated that the parasitic capacitance betweenneighboring or adjacent portions of the conductors or coils may bedetermined by the dielectric constant of the material arranged betweenthe respective conductors, the distance between the conductors, and theshape and/or area of the conductors.

By varying one or several of those parameters, such as, e.g., the trackwidth or track spacing of the coils, the parasitic capacitance betweencoils extending in the same plane may be adapted so as to provide adesired shunt capacitance without using additional shunt capacitors.Further, the track width, distance, or dielectric constant betweensuperposing coils may be modified so as to provide a desired couplingcapacity without using additional coupling capacitors.

In one example, the dielectric constant of the intermediate layer andthe distance between the first layer and the second layer may be givenby the technology wherein the coupling element is implemented, and maytherefore be difficult to modify or vary. In such cases, the couplingcapacitance, e.g. the parasitic capacitance between the first coil andthe third coil (and the second coil and the fourth coil, respectively),may be determined by the width of the conducting traces forming therespective coils. Increasing the width of the traces may increase thecoupling capacitance, whereas reducing the width may result in a reducedcoupling capacitance.

According to an embodiment, the coupling element may comprise four portsthat are formed by electrical terminals of the coils: a differentialinput port, a differential through port, a differential coupled port,and a differential isolated port. The differential input port may beformed by a first terminal of the first coil and a first terminal of thesecond coil, the differential through port by a second terminal of thefirst coil and a second terminal of the second coil, a differentialcoupled port by a second terminal of the third coil and a secondterminal of the fourth coil, and a differential isolated port by a firstterminal of the third coil and a first terminal of the fourth coil.During operation, at least a portion of the power applied to thedifferential input port may be transmitted to the differential throughport, at which the transmitted power may be output. Further, a portionof the input power may also be transmitted or coupled to differentialcoupled port, at which the coupled power may be output at a phasedifference. The isolated port may be terminated with a matched load soas to provide a directional coupler.

According to an embodiment, the differential input port and thedifferential through port may be arranged on a first side of thecoupling element, whereas the differential coupled port may be arrangedon a second side of the coupling element. The differential isolated portmay also be arranged on the second side of the coupling element. Thefirst side and the second side of the coupling element may be differentand arranged so as to facilitate or simplify the layout of the circuitin which the coupling element is used.

In one embodiment, the first side and the second side may be arrangedopposite to each other so as to facilitate a cascade or chain connectionof several coupling elements.

It will be appreciated that the coils may be routed such that an innerperiphery of the coupling element conforms to a polygon, such as arectangle, square, or octagon, or a ring shape such as a circle or oval.

According to an embodiment, at least one of the first coil, the secondcoil, the third coil, and the fourth coil may comprise a via connectionfor electrically connecting the at least one turn in the first layerwith said another turn in the second layer, respectively. The viaconnection may hence provide an electrical connection betweenelectrically conducting traces in the first layer and the second layer,thus allowing an electrical signal to be conducted through theintermediate dielectric layer. The coil may extend in a generally spiralfashion such that a terminal of the coil is arranged on an outsideportion of the coupling element and the via connection within thecoupling element.

According to a second aspect, a semiconductor device is provided,comprising a coupling element according to the first aspect. As thecoupling element may be arranged in two conducting layers, on-chipintegration of the coupling element may be implemented by using only twometal layers of the semiconductor device for forming the first layer andthe second layer of the coupling element. For a high quality of theperformance of the coupling element, the electrical resistance of theconductors of the coils may be as low as possible. Metal layers maytherefore be well suited for this.

According to some embodiments, the coupling element may be implementedin a monolithic microwave integrated circuit, MMIC, or a complementarymetal oxide semiconductor, CMOS, integrated circuit. The power and/orground layers may be used as the first and the second layers of thecoupling device. As the power and/or ground layers in standard CMOStechnology may be thicker than the other metal layers, tracks of a givenwidth may have less electrical resistance in these thicker layers andmay therefore provide a coupling element having improved electricalcharacteristics.

According to a third aspect, a differential hybrid coupler is provided,comprising a coupling element according to the first aspect. Thedifferential hybrid coupler further comprises a termination resistorthat is connected to the differential isolated port formed by the firstterminal of the third coil and the first terminal of the fourth coil.The differential hybrid coupler may be designed to provide a 3 dBcoupling, but other coupling values (e.g., 10 dB) may be also provideddepending on the required specification. The phase difference betweenthe differential through port and the differential coupled port may,e.g., be 90 degrees such that the differential coupled port is inquadrature phase with the differential through port. A differentialquadrature coupler thereby may be provided.

As already mentioned, the coils of the coupling element according to thefirst aspect may be formed of electrical conductors having a track widthand/or spacing that is adapted to provide a desired coupling capacitanceand/or shunt capacitance. However, the differential hybrid coupler mayalso be provided with additional capacitors. According to an embodiment,the differential hybrid coupler may comprise a first set of couplingcapacitors that is connected between the differential input port and thedifferential coupled port, and a second set of coupling capacitors thatis connected between the differential through port and the differentialisolated port so as to provide a desired coupling capacitance. In oneexample, the first set of coupling capacitors may comprise a capacitorconnected between the first terminal of the first coil and a secondterminal of the third coil, and another capacitor connected between thefirst terminal of the second coil and the second terminal of the fourthcoil. The second set of coupling capacitors may comprise a capacitorconnected between the second terminal of the first coil and the firstterminal of the third coil, and another capacitor connected between thesecond terminal of the second coil and the first terminal of the fourthcoil.

Further, a shunt capacitor may be provided between the terminals of eachrespective port. For example, a first shunt capacitor may be connectedbetween the terminals of the differential input port, i.e., the firstterminal of the first coil and the first terminal of the second coil.Similarly, a second shunt capacitor may be connected between theterminals of the differential through port, i.e. the second terminal ofthe first coil and the second terminal of the second coil, a third shuntcapacitor may be connected between the terminals of the differentialcoupled port, i.e. the second terminal of the third coil and the secondterminal of the fourth coil, and, a fourth capacitor may be connectedbetween terminals of the differential isolated port, i.e. the firstterminal of the third coil and the first terminal of the fourth coil, soas to provide a desired shunt capacity.

Further objectives of, features of, and advantages with the presentdisclosure will become apparent when studying the following detaileddisclosure, the drawings, and the appended claims. Those skilled in theart realize that different features of the present disclosure, even ifrecited in different claims, can be combined in embodiments other thanthose described in the following.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a coupling element arranged in a firstlayer and a second layer, according to example embodiments.

FIG. 2 is a schematic layout of the turns of a coupling element arrangedin the first layer, according to example embodiments.

FIG. 3 is a schematic layout of the turns of a coupling element arrangedin the second layer, according to example embodiments.

FIG. 4 is a schematic cross-section of a portion of the layers of acoupling element, according to example embodiments.

FIG. 5 is a symbolic representation of a semiconductor device, such as adifferential hybrid coupler, according to example embodiments.

DETAILED DESCRIPTION

The present disclosure will now be described hereinafter with referenceto the accompanying drawings, in which embodiments of the disclosure areshown. This disclosure may, however, be embodied in many different formsand should not be construed as limited to the embodiments set forthherein.

With reference to FIG. 1, there is shown a perspective view of acoupling element 10 according to an embodiment of present disclosure.The coupling element may comprise four coils 100, 200, 300, 400, each ofwhich having at least two turns extending in a first layer and a secondlayer, respectively.

As indicated in FIG. 1, the first coil 100 comprises a first terminal112 and a second terminal and may be arranged such that at least oneturn 110, forming a part of the coil 100, extends in the first layer andat least another turn 120 extends in the underlying, second layer. Thefirst and second layers, and hence the respective turns 110, 120 of thefirst coil 100, may be separated from each other by an intermediatedielectric layer as shown in FIG. 4.

According to the present embodiment, the first terminal 112 and thesecond terminal 122 of the first coil 100 may be arranged on a same sideof the coupling element 10 such that, during operation of the couplingelement 10, power that is input at, e.g., the first terminal 112 may beoutput at the same side of the coupling element 10.

The second coil 200 may be similarly arranged as the first coil 100,extending in the first layer and the second layer and having a firstterminal 212 and a second terminal 222. Further, the second coil 200 maybe arranged such that at least one turn 210 of the second coil 200extends in the first layer and along at least a portion of the firstcoil 100, i.e., along, or side by side with, at least a portion of theat least one turn 110 arranged in the first layer. Further, another turn220 of the second coil may be arranged to extend in the second layer andalong at least a portion of the first coil 100, i.e., along at least aportion of the turn 120 of the first coil 100 arranged in the secondlayer.

By arranging the first coil 100 and the second coil 200 such that thefirst terminal 112 of the first coil 100 is connected to the turn 110 ofthe first coil 100 that extends in the first layer, and such that thefirst terminal 212 of the second coil 200 is connected to the turn 220of the second coil 200 that extends in the second layer, the first coil100 and the second coil 200 can be described as two oppositely routedcoils. Accordingly, the second terminal 122 of the first coil 100 isconnected to the turn 120 of the first coil 100 that extends in thesecond layer, whereas the second terminal 222 of the second coil 200 isconnected to the turn 220 of the second coil 200 that extends in thefirst layer. By arranging the second coil 200 such that it at leastpartly extends along the first coil 100 in a same plane, a parasiticcapacitance, or shunt capacitance, between the first coil 100 and thesecond coil 200 may be used to provide or modify a characteristicimpedance of the coupling element. Further, as a signal is provided atthe first terminal 112 and the second terminal 212, the opposite routingof the first coil 100 and the second coil 200 allows for a differentialsignaling; wherein the electromagnetic fields that are generated by thecomplementary signals are directed in the same direction, therebyavoiding, or at least reducing, the risk of the magnetic fieldscancelling or counteracting each other.

The third coil 300 and the fourth coil 400 may be similarly arranged asthe first coil 100 and the second coil 400. As indicated in FIG. 1, atleast one turn 310 of the third coil 300 may be arranged to extend inthe first layer and such that it superposes at least a portion 120 ofthe first coil arranged in the second layer. Further, another turn 320of the third coil is arranged to extend in the second layer and tosuperpose at least a portion 110 of the first coil 100 arranged in thefirst layer. By arranging the third coil 300 such that it at leastpartly superposes the first coil 100, i.e., such that the first coil 100and the third coil 300 are arranged in a stacked arrangement in relationto each other, an electromagnetic interaction may be provided. Theelectromagnetic interaction may allow for a transformer action betweenthe first coil 100 and the third coil 300. The third coil 300 may have afirst terminal 312 connected to the turn 320 of the third coil 300 thatis arranged in the second layer, and a second terminal 322 connected tothe turn 310 of the third coil 300 that is arranged in the first layer.

The fourth coil 400 may comprise at least one turn 410 that is arrangedto extend in the first layer and such that it superposes at least aportion 220 of the second coil 200 arranged in the second layer, and atleast one turn 420 that is arranged to extend in the second layer andsuch that it is superposed by at least a portion 210 of the second coil200 arranged in the first layer. Further, the fourth coil 400 maycomprise a first terminal 412 that is connected to the turn 410 arrangedin the first layer, and a second terminal 422 that is connected to theturn 420 arranged in the second layer. Similarly to what is describedabove in connection to the third coil 300, a transformer coupling may beprovided between the fourth coil 400 and the second coil 200.

As the third coil 300 and the fourth coil 400 may be routed or operatedin opposite direction, they may be used for differential signaling in asimilar way as described with reference to the first coil 100 and thesecond coil 200.

The coupling element 10 may further comprise a differential input portP1 that is formed by the first terminal 112 of the first coil 100 andthe first terminal 212 of the second coil 200. The second terminal 122of the first coil 100 and the second terminal 222 of the second coil 200may form a differential through port P2, wherein the differential inputport P1 and the differential through port P2 may be arranged on the sameside of the coupling element 10. Similarly, the first terminal 312 ofthe third coil 300 and a first terminal 412 of the fourth coil 400 mayform a differential isolated port P4, whereas the second terminal 322 ofthe third coil 300 and a second terminal 422 of the fourth coil 400 mayform a differential coupled port P3.

FIG. 2 is a schematic illustration of the layout or routing of acoupling element 10 in the first layer. The coupling element 10 may besimilarly configured as the coupling element 10 discussed in connectionwith FIG. 1. As shown in FIG. 2, the first layer of the presentembodiment may comprise one turn 112, 212, 312, 412 of each one of thefirst coil 100, second coil 200, third coil 300, and fourth coil 400,respectively. The turn 110 of the first coil 100 starts at the firstterminal 112, arranged at a first side of the coupling element, andends, after a, e.g., counter-clockwise turn, at a first via connection130 arranged within the coupling element 10 and at a same side of acenter point of the coupling element as the first side. The turn 210 ofthe second coil 200 may start at a second via connection 230, which maybe arranged adjacent to the first via connection 130, and extendclockwise along the turn 110 of the first coil 100 to a second terminal222 of the second coil 200, arranged at the same side of the couplingelement 10 as the first terminal 122 of the first coil 100.

Similarly, the turn 410 may, according to this embodiment, start at thefirst terminal 412 of the fourth coil 400 and end, after a counterclockwise turn, at a fourth via connection 430 arranged within thecoupling element 10. Adjacent to the fourth via connection 430, a thirdvia connection 430 may be arranged from which the turn 310 of the thirdcoil 300 may extend clockwise to the second terminal 322 of the thirdcoil 300, wherein the second terminal 322 may be arranged at the sameside of the coupling element 10 as the first terminal 412 of the fourthcoil 400. In this embodiment, the first terminal 412 of the fourth coil400 and the second terminal 322 of the third coil 300 may be arranged ata second side of the coupling element 10, wherein the second side may beopposite to the first side.

The via connections 130, 230, 330, 430 may be configured to electricallyconnect the portions of the coils 100, 200, 300, 400 in the first layerwith the portions of the coils 100, 200, 300, 400 in the second layer.

An example of such a second layer of a coupling element is shown in FIG.3. The embodiment in FIG. 3 may be similarly configured as the couplingelements described with reference to FIGS. 1 and 2. As shown in FIG. 3,the turn 120 of the first coil 100 starts at the via 130 and continuescounterclockwise to the second terminal 122 of the first coil 100, theturn 220 starts at the first terminal 212 of the second coil 200 andcontinues clockwise along the turn 120 of the first coil 100 to the viaconnection 230, the turn 320 of the third coil 300 starts at the firstterminal 312 of the third coil 300 and continues clockwise to the thirdvia connection 330, and the turn 420 of the fourth coil 400 starts atthe fourth via connection 430, adjacent to the third via connection 330,and continues counterclockwise to the second terminal 422 of the fourthcoil 400.

As shown in FIGS. 1-3, the tracks forming the turns of the coils 100,200, 300, 400 in each layer may extend along a spiral allowing theterminals to be connected from outside of the coupling element 10 andthe via connections 130, 230, 330, 430 to be arranged within thecoupling element 10.

FIG. 4 is a schematic cross section of a portion of a coupling elementthat may be similarly configured as any one of the previously describedembodiments. As illustrated in FIG. 4, the coupling element may bearranged in a stacked configuration wherein each coil (not shown in FIG.4) may be arranged such that at least one turn extends in the firstlayer 11 and at least another turn extends in a second layer 12. Thelayers may be separated from each other by a dielectric intermediatelayer 13. Further, a via connection 130, 230, 330, 430 may extendthrough the intermediate layer 13 so as to allow for an electricalconnection between the first layer 11 and the second layer 12. In someembodiments, the first layer 11 and the second layer 12 may be metallayers, or conducting layers, of an integrated circuit.

FIG. 5 is a symbolic representation of a semiconductor device, such as adifferential hybrid coupler, comprising a coupling element 10 accordingto any one of the embodiments described with reference to FIGS. 1-4. Thecoupling element comprises a differential input port P1, a differentialthrough port P2, a differential coupled port P3 and a differentialisolated port P4 as previously described.

According to the present embodiment, the differential hybrid coupler maycomprise a termination resistor R, or matched load, that is connected tothe differential isolated port P4. Further, coupling capacitors Cc1,Cc2, Cc3, Cc4 may be arranged at one or several of the differentialinput port P1, the differential through port P2, the differentialcoupled port P3, and the differential isolated port P4. A first couplingcapacitor Cc1 may be connected between the first terminal 112 of thefirst coil 100 and a second terminal 322 of the third coil 300, a secondcoupling capacitor Cc2 connected between the second terminal 122 of thefirst coil 100 and the second terminal 322 of the third coil 300, athird coupling capacitor Cc3 connected between the first terminal 212 ofthe second coil 200 and the second terminal 422 of the fourth coil 400,and a fourth coupling capacitor Cc4 connected between the secondterminal 222 of the second coil 200 and the first terminal 412 of thefourth coil 400.

Further, shunt capacitors Cs1, Cs2, Cs3, Cs4 may be provided between theterminals of one or several of the ports P1, P2, P3, P4. In one example,a first shunt capacitor Cs1 may be connected between the first terminal112 of the first coil 100 and the first terminal 212 of the second coil200, a second shunt capacitor Cs2 connected between the second terminal122 of the first coil 100 and the second terminal 222 of the second coil200, a third shunt capacitor Cs3 connected between the second terminal322 of the third coil 300 and the second terminal 422 of the fourth coil400, and a fourth shunt capacitor Cs4 connected between the firstterminal 312 of the third coil 300 and the first terminal 412 of thefourth coil 400.

In conclusion, a coupling element is disclosed. The coupling elementcomprises four coils that are arranged such that each one of the coilsextends both in a first layer and a second layer. The first layer andthe second layer are stacked with respect to each other and separated byan intermediate dielectric layer. The layout of each layer is configuredto provide a transformer coupling between a first one and a third one ofthe coils, and between a second one and a fourth one of the coils,respectively. Further, the first coil and the second coil, and the thirdcoil and the fourth coil, respectively, are routed so as to allow adifferential signaling. A semiconductor device and a differential hybridcoupler comprising the coupling element are also disclosed.

While the present disclosure has been illustrated and described indetail in the appended drawings and the foregoing description, suchillustration and description are to be considered illustrative orexemplifying and not restrictive; the present disclosure is not limitedto the disclosed embodiments. Other variations to the disclosedembodiments can be understood and effected by those skilled in the artin practicing the claimed disclosure, from a study of the drawings, thedisclosure, and the appended claims. For example, the routing or tracesof the coils may be provided in any suitable shape, conforming to, e.g.,octagons or ring-shapes, and is not limited to the exemplifyingembodiments disclosed in connection with the figures. Further, thenumber of turns of the coils may be varied, just as the position of thecorresponding terminals.

The mere fact that certain measures are recited in mutually differentdependent claims does not indicate that a combination of these measurescannot be used to advantage. Any reference signs in the claims shouldnot be construed as limiting the scope.

What is claimed is:
 1. A coupling element arranged in a first layer anda second layer that are separated from each other by an intermediatedielectric layer, the coupling element comprising: a first coil arrangedsuch that: at least one turn of the first coil extends in the firstlayer, and another turn of the first coil extends in the second layer; asecond coil arranged such that: at least one turn of the second coilextends in the first layer and along at least a portion of the firstcoil arranged in the first layer, and another turn of the second coilextends in the second layer and along at least a portion of the firstcoil arranged in the second layer; a third coil arranged such that: atleast one turn of the third coil extends in the first layer andsuperposes at least a portion of the first coil arranged in the secondlayer, and another turn of the third coil extends in the second layerand superposes at least a portion of the first coil arranged in thefirst layer; and a fourth coil arranged such that: at least one turn ofthe fourth coil extends in the first layer and superposes at least aportion of the second coil arranged in the second layer, and anotherturn of the fourth coil extends in the second layer and superposes atleast a portion of the second coil arranged in the first layer.
 2. Thecoupling element according to claim 1, further comprising: adifferential input port formed by a first terminal of the first coil anda first terminal of the second coil; a differential through port formedby a second terminal of the first coil and a second terminal of thesecond coil; a differential coupled port formed by a second terminal ofthe third coil and a second terminal of the fourth coil; and adifferential isolated port formed by a first terminal of the third coiland a first terminal of the fourth coil.
 3. The coupling elementaccording to claim 2, wherein: the differential input port and thedifferential through port are arranged on a first side of the couplingelement; and the differential coupled port and the differential isolatedport are arranged on a second side of the coupling element, wherein thefirst side of the coupling element and the second side of the couplingelement are different sides of the coupling element.
 4. The couplingelement according to claim 3, wherein the first side of the couplingelement and the second side of the coupling element are arrangedopposite to each other.
 5. The coupling element according to claim 1,wherein an inner periphery of the coupling element conforms to a polygonshape or a ring shape.
 6. The coupling element according to claim 1,wherein at least one of the first coil, the second coil, the third coil,and the fourth coil comprises a via connection for electricallyconnecting the at least one turn in the first layer with the anotherturn in the second layer, respectively.
 7. The coupling elementaccording to claim 1, wherein the first coil, the second coil, the thirdcoil, and the fourth coil are formed by metal traces.
 8. A semiconductordevice, comprising: a coupling element arranged in a first layer and asecond layer that are separated from each other by an intermediatedielectric layer, the coupling element comprising: a first coil arrangedsuch that: at least one turn of the first coil extends in the firstlayer, and another turn of the first coil extends in the second layer; asecond coil arranged such that: at least one turn of the second coilextends in the first layer and along at least a portion of the firstcoil arranged in the first layer, and another turn of the second coilextends in the second layer and along at least a portion of the firstcoil arranged in the second layer; a third coil arranged such that: atleast one turn of the third coil extends in the first layer andsuperposes at least a portion of the first coil arranged in the secondlayer, and another turn of the third coil extends in the second layerand superposes at least a portion of the first coil arranged in thefirst layer; and a fourth coil arranged such that: at least one turn ofthe fourth coil extends in the first layer and superposes at least aportion of the second coil arranged in the second layer, and anotherturn of the fourth coil extends in the second layer and superposes atleast a portion of the second coil arranged in the first layer.
 9. Thesemiconductor device according to claim 8, wherein the first layer andthe second layer are metal layers.
 10. The semiconductor deviceaccording to claim 8, wherein the coupling element is implemented in amonolithic microwave integrated circuit, MMIC.
 11. The semiconductordevice according to claim 8, wherein the coupling element is implementedin a complementary metal oxide semiconductor, CMOS, integrated circuit.12. A differential hybrid coupler, comprising: a coupling elementarranged in a first layer and a second layer that are separated fromeach other by an intermediate dielectric layer, the coupling elementcomprising: a first coil arranged such that: at least one turn of thefirst coil extends in the first layer, and another turn of the firstcoil extends in the second layer; a second coil arranged such that: atleast one turn of the second coil extends in the first layer and alongat least a portion of the first coil arranged in the first layer, andanother turn of the second coil extends in the second layer and along atleast a portion of the first coil arranged in the second layer; a thirdcoil arranged such that: at least one turn of the third coil extends inthe first layer and superposes at least a portion of the first coilarranged in the second layer, and another turn of the third coil extendsin the second layer and superposes at least a portion of the first coilarranged in the first layer; and a fourth coil arranged such that: atleast one turn of the fourth coil extends in the first layer andsuperposes at least a portion of the second coil arranged in the secondlayer, and another turn of the fourth coil extends in the second layerand superposes at least a portion of the second coil arranged in thefirst layer; and a termination resistor connected to a differentialisolated port formed by a first terminal of the third coil and a firstterminal of the fourth coil.
 13. The differential hybrid coupleraccording to claim 12, wherein an inner periphery of the couplingelement conforms to a polygon shape or a ring shape.
 14. Thedifferential hybrid coupler according to claim 12, wherein at least oneof the first coil, the second coil, the third coil, and the fourth coilcomprises a via connection for electrically connecting the at least oneturn in the first layer with the another turn in the second layer,respectively.
 15. The differential hybrid coupler according to claim 12,wherein the first layer and the second layer are metal layers.
 16. Thedifferential hybrid coupler according to claim 12, further comprising: adifferential input port formed by a first terminal of the first coil anda first terminal of the second coil; a differential through port formedby a second terminal of the first coil and a second terminal of thesecond coil; and a differential coupled port formed by a second terminalof the third coil and a second terminal of the fourth coil.
 17. Thedifferential hybrid coupler according to claim 16, further comprising: afirst set of coupling capacitors connected between the differentialinput port and the differential coupled port; and a second set ofcoupling capacitors connected between the differential through port andthe differential isolated port.
 18. The differential hybrid coupleraccording to claim 16, further comprising: a first shunt capacitorconnected between the terminals of the differential input port, a secondshunt capacitor connected between the terminals of the differentialthrough port, a third shunt capacitor connected between the terminals ofthe differential coupled port, and a fourth shunt capacitor connectedbetween the terminals of the differential isolated port.
 19. Thedifferential hybrid coupler according to claim 16, wherein thedifferential input port and the differential through port are arrangedon a first side of the coupling element; and the differential coupledport and the differential isolated port are arranged on a second side ofthe coupling element, wherein the first side of the coupling element andsecond side of the coupling element are different sides of the couplingelement.
 20. The differential hybrid coupler according to claim 19,wherein the first side of the coupling element and the second side ofthe coupling element are arranged opposite to each other.